Tubular extrusion apparatus and method



Oct. 18, 1966 F. w. HASS ET AL 3,279,231

TUBULAR EXTRUSION APPARATUS AND METHOD Filed D60. 19, 1965 2 Sheets-Sheet l INVENTORS FOSTER W. HASS 81 CARL R. ANDERSON ATTORN EY Oct. 18, 1966 F. w. HAss ET AL 3,279,231

TUBULAR EXTRUSION APPARATUS AND METHOD Filed Dec. 19, 1963 2 Sheets-Sheet 2 INVENTORS FOSTER W. HASS a CARL R. ANDERSON ATTORNEY United States Patent 3,279,231 TUBULAR EXTRUSION APPARATUS AND METHOD Foster W. Hass, Monticello, and Carl R. Anderson, West Lafayette, Ind, assignors to Aluminum Company of America, Pittsburgh, Pa., a corporation of Pennsylvania Filed Dec. 19, 1963, Ser. No. 331,759 Ciaims. (Ci. 72273) This invention relates in general to improved extrusion apparatus and method of extrusion, and is more particularly concerned with the incorporation of new and im proved structural features in existing conventional and newly constructed extrusion equipment to permit and provide increased productivity of tubular extruded products therefrom.

It is recognized and accepted engineering design practice, in horizontal extrusion equipment, to dimensionally select and fix the linear or axial distance between the front and rear platens of an extrusion press for any given axial length of the billet and/ or ingot-receiving and laterallyconfining cylinder or container conventionally located between the platens. It is likewise conventional practice to provide a power ram of sufficient axial length to accommodate and permit axial translation thereof a distance substantially equal to the axial length of the aforesaid billet cylinder or container to insure substantially full and efficient use of the productive capacity of an extrusion press.

Such dimensional relationship between the length of the billet cylinder, the length of billet charged therein to be extruded, and the effective length of the power ram and distance of travel or stroke thereof, would all be equal for most efficient productive capacity of the extrusion equipment so characterized. The aforesaid dimensional equality manifestly also establishes economical use of floor space required for any given efficiently de signed extrusion press.

The aforesaid dimensional characteristics prevail universally in regard to direct extrusion equipment for producing solid bar, rod and similar extruded products. However, on adaptation of the dimensionally identical conventional extrusion equipment to the production of hollow or tubular extruded products, it has been conventionally accepted practice to provide a rigid mandrel in axially extending alignment to and carried or supported by the power ram, with the axial length of the mandrel shorter than the power ram stroke, as well as being shorter in axial length than the usable billet cylinder length, to thereby penalize the capacity of the extrusion press in regard to the length of billet and finished tubular extrusion capable of production thereby. This will be readily appreciated when it is considered conventional and essential practice to provide a one-piece dummy block in surrounding assembly on the mandrel, in its retracted position, by introducing the dummy block laterally into the clearance area between the forward end of the retracted and shorter mandrel and rear or adjacent breech face of the appreciably longer billet container for rearward axial sliding assembly and support of the one-piece dummy block on the mandrel.

There are additional explanations why the mandrel controlling and defining the interior bore of a tubular extru sion is conventionally selected of shorter axial length than the ram stroke and full axial length of the billet-receiving cylinder, economy in floor space, or the fixed distance between front and rear platens of the extrusion press, as well as standardization by equipment manufacturers being regularly encountered reasons.

It is therefore an object of the present invention to provide a dummy block structure which is capable of instal lation in segments in mandrel-surrounding and supported relationship in respect to an extrusion press under design and structural dimensional limitations wherein the mandrel purposely extends into the billet cylinder in its fully retracted position prior to the start of an extrusion operation to thereby obviate conventional axial installation and use of a conventional one-piece dummy block.

Another object .of the invention is to provide a segmented dummy block which permits increased productivity of conventional extrusion equipment, which by its inherent characteristic structural limitations, is incapable of employing the full axial length of its billet or ingot cylinder for producing tubular extrusions.

It is also an object of the invention to provide new and improved extrusion practices employing conventional extrusion equipment to the end of increasing the productivity of the equipment in the production of tubular extrusions.

Other objects and advantages will be appreciated by those skilled in the art to which the present invention is addressed on consideration of the following detailed description of the improved extrusion apparatus, the method steps performed thereby, and the appended drawings, in which:

FIG. 1 represents a somewhat diagrammatic side elevational View, in partial section, of a horizontal hydraulic extrusion press with which the present invention has been practiced;

FIG. 2 represents an enlarged side elevational view, in partial section, of a portion of the equipment of FIG. 1 illustrating installation of the improved segmented dummy block of the invention;

FIG. 3 represents a side elevational view, in partial section and to further enlarged scale, of the assembled and installed improved segmented dummy block of the invention;

FIG. 4 represents a front elevational view of the working face of the dummy block, as viewed from the left of FIG. 3; and

FIG. 5 represents a fragmentary view in the direction of the arrows 5-5 in FIG. 4.

In its broadest concept, the present invention relates to a new and improved dummy block structure which is employable with otherwise conventional existing and newly constructed extrusion equipment for producing tubular extrusions from hollow or tubular billets or ingots, but in which extrusion equipment the mandrel controlling the interior configuration of the finished extrusions, as a result of structural and dimensionally fixed features of the extrusion equipment, extends or projects into the interior of a hollow billet or ingot charged into the billet and laterally-confining billet cylinder or container of the extrusion equipment as an essential and controlling feature thereof preliminary to performance of an extrusion operation therewith.

Referring to the drawings, and particularly FIG. 1, a conventional horizontal direct extrusion press has been illustrated which comprises a front platen 10 and rear platen 12 coupled in stationary pressure-restraining relations-hip by means of at least three suitable tie or strain rods 14. The front platen 10 is apertured. or tunnelled at 16 for reciprocally receiving a conventional tool carriage assembly, identified in its entirety at 18, which includes a replaceable female transverse exterior configurationcontrolling die 20 and one or more replaceable apertured back-up discs or blocks 22 of selected thicknesses to insure proper disposition of the die 20 in pressure-resistant sealing relationship with the discharge or muzzle end of a billet container or ingot-receiving cylinder 24 of the press.

A bifurcated locking bar 26 is provided for reciprocal translation into and out of abutment against the discharge face of the tool carriage assembly 18, remote to the extrusion die 2%, and a power-actuated connecting 3 rod 28 connected to the tool carriage 18 permits and provides means for translating the same to a location beneath or adjacent a shear blade Si), or equivalent severing device, such as a rotary saw or the like, on Withdrawal .of the aforesaid locking bar 26 at the completion of an 'as in axial alignment with the aforementioned billetreceiving cylinder 24. Fluid, such as high pressure water from an accumulator, delivered to the rear end of the cylinder 34 drives the piston 36, cross-head 38 and ram 40 in a forward direction toward the front platen It) in a power stroke of the extrusion equipment, the return or retracting stroke of the same integrated elements being accomplished by oppositely disposed low fluid pressure power-actuated auxiliary pull-back cylinders 42 interconnected to the cross-head 38 and suitably supported on the outer surface of the rear platen 12 and cylinder 34. The cross-head 38 is preferably slidingly supported on oppositely disposed stationary rails 44.

The aforementioned billet and/or ingot-receiving cylinder or container 24 may be supported in fixed or stationary disposition in respect to the entrance face to the tunnel 16 in the front platen l and/ or entrance face to the extrusion die 20. In an alternative conventional extrusion press construction the cylinder 24 may he slidably supported on extensions of the oppositely disposed stationary rail members 44, or equivalent structure, for rearward translation away from the entrance face to the tunnel 16 to a position axially overlying and coextensive With the ram 40, or even into abutment against the retracted cross-head 38, to provide clearance for conventional muzzle loading or charging of an ingot or billet into the cylinder 24 between the front face of the platen and muzzle face of the billet cylinder 24. Oppositely disposed low fluid pressure power-actuated auxiliary cylinders 46 are conventionally employed in interconnected association with the stationary front platen 10 and cylinder or container 24, where the latter is of the reciprocal type last described.

The mandrel essential to the production of tubular extrusions is identified by the reference numeral 50 and, as stated in the forepart of the specification, is carried by the ram 40 as an axially extending forward extension thereof. Conventionally in the extrusion art, the mandrel 50 may be a rigid extension carried by the ram 40, or it may be mounted telescopically within an axial bore through the ram 40 and piston 36 with its rear end received within a fluid pressure cylinder 52 providing independent reciprocation of the mandrel relative to the ram 40.

Regardless of the structural design and means for supporting the mandrel 50, that is, whether the mandrel 50 is provided as a rigid extension of the ram 40, or as an independently translatable member relative to the ram 40, it is a significant characteristic of the mandrel 50 that its axially extending length in advance of the power ram 40, at the start or beginning of an extrusion operation, as illustrated in full line construction in FIG. 1, is substantially equal to the maximum axial length of the billet cylinder 24 to thereby locate its forward end within the female die 20 at the start of extrusion to impart a desired interior configuration to the tubular product to be extruded. Otherwise, a shorter axial length of the mandrel 50 would necessitate selection of an initial billet length less than the useful axial length and capacity of the cylinder 24 and axial travel or power stroke of the ram 40 conventionally provided and available in extrusion presses employing the full axial power stroke of the ram and full axial length of the billet-receiving cylinder in the production of solid bar and similar non-tubular extruded products from initial billets approaching or equalling the axial length of the cylinder confining the same.

The cardinal and improved feature over and above otherwise conventional extrusion equipment thus far described and explained hereinabove, lies in the substitution for, or replacement of, the conventionally employed solid ring type dummy block, in surrounding assembly on the mandrel of such conventional extrusion apparatus, with a segmented dummy block, identified in its entirety by the reference numeral 54.

The dummy block 54 (FIG. 2) is preferably constructed in three parts and comprises a rear one-piece back-up member 56 provided with a bore or aperture 58 (FIG. 3) therethrough conforming substantially to the exterior axially uniform transverse cross-sectional profile of the mandrel 50. The interior bore 58 is preferably bushed with one or more close tolerance friction-reducing lands, such as bronze liners 60, as an aid to facile sliding mounting of the one-piece member 56 axially over the mandrel 50. The outside diameter of the one-piece backup member 56 preferably conforms in exterior contour or configuration to the axial bore in the billet-receiving cylinder 24, but is purposely selected appreciably smaller than the aforesaid bore to provide ample clearance therewithin and non-interference slidable translation therethrough over the axial length of the mandrel 50.

The forward portion of the dummy block 54 is preferably selected in the form of two perimetrically matching segments 62 and 64 centrally configurated to conform to and peripherally surround the transverse profile of the mandrel 5d and provide an outer perimetrical scavenging flange 66 of close tolerance sliding conformity within the bore in the billet cylinder or container 24. The scavenging flange 66 is otherwise relatively thin in the axial thickness direction of the segments 62 and 64 and is preferably formed as an outwardly stepped projecting land surrounding the matching perimetrical ledge surfaces 68 of each of the segments 62 and 64. Each of the segments 62 and 64 can, if desired, be also bushed to provide reduced frictional axial translation relative to the mandrel supporting the same, as in the case of the one-piece rear element 56 of the dummy block 54.

The front exposed pressure-exerting face of the assembled segments 62 and 64 is selected and designed to provide a generally convex surface facing towards the breech end of the billet cylinder 24 contactable with the adjacently disposed rear end of a billet 70 charged therein. As illustrated to best advantage in FIGS. 3 and 4, the generally convex front working face or surface presented by the assembled segments 62 and 64 is radially outwardly and rearwardly sloped at 72 from a relatively fiat forwardly extending central area 74, the purpose of which Will be hereinafter explained in more detail.

In addition, the opposite or rear face presented by the assembled dummy block segments 62 and 64 provides a rearwardly projecting tenon 76 receivable Within a configuratively matching mortised recess 78 in the one-piece back-up dummy block member or element 56. In this connection the outer defining peripheries 80 and 82 of the tenon 76 and recess 78, respectively, provide axially matching tapered pilot surfaces.

It will be apparent that the split or two-piece construction of the dummy block segments 62 and 64 permits lateral assembly of the same around the mandrel 50, as illustrated in FIGS. 2 and 3. It will also be observed that axial translation of the assembled segments 62 and 64 to enter the tenon 76 thereof within the recess 78 in the one-piece back-up dummy block element 56 serves to retain and secure the otherwise laterally separable segments 62 and 64 against radial or lateral separation. This retaining or restraining feature can be further enhanced by complementary half keyways 84 and a key 86 inserted therewithin. The key and keyway securing structure is best illustrated in FIGS. 4 and 5, the key and half keyways being symmetrically formed and oppositely angulated in transverse configuration against circumferential separation of the segments 62 and 64. The key 36 is also preferably drilled and tapped at 88 to receive a suitable replaceable threaded key-withdrawing or extractor tool, or puller, to permit lateral separation of the segments 62 and 64, when desired. The restraining key and keyway construction 8486 is also beneficial to unitary recovery of the assembled segments 62 and 64 on completion of an extrusion operation, as will be more fully explained hereinafter.

In the operation and practice of the invention, and referring to FIG. 1, a tubular billet 70 is charged into the cylinder or container 24 in conventional manner. This charging operation can be accomplished axially through the tunnel 16 in the front platen, on outward reciprocation of the tool assembly carriage l8 therefrom, or it can also be conventionally carried out by translation of the cylinder 24 rearwardly over and relative to the mandrel 5t) and ram 40 in retracted position of the latter to provide sufficient axial clearance between the muzzle end of the cylinder 24 and rear tunnelled surface of the front platen to receive the billet '70, the cylinder 24 being thereafter translated forwardly over the tubular billet "70 following axial alignment therebetween. Regardless of the technique employed to charge a tubular billet 70 within the container or cylinder 24 of the extrusion press illustrated in FIG. 1, it is a prevailing and structurally dimensional characteristic of the equipment that the mandrel 50 extends axially into the bore of the cylinder 24 and tubular billet 70 to bridge or span the otherwise unobstructed axial space or distance between the breech end of cylinder 24, in its forward position adjacent the front platen 10, and forward face of the ram 40, in its fully retracted position, to thereby prevent assembly or installation of a conventional apertured one-piece dummy block in surrounding relationship on the mandrel 50 from the breech end of the extrusion press.

This seemingly impossible dummy block installing situation has been overcome by providing the segmented dummy block 54 which permits retention of its one-piece back-up element 56 in surrounding assembly on the mandrel 50 at all times, or its axial translated assembly over the mandrel 50 at any time, even to include clearance introduction and sliding placement thereof through the axial length of the billet cylinder 24 from the muzzle or dis charge end thereof, because of the purposely provided on dersize outer peripheral dimensions of the element 56 in respect to the bore in cylinder 24.

Subsequent assembly and installation of the dummy block segments 62 and 64 follows the procedure illustrated in FIGS. 2 and 3, each of the segments being advanced laterally inwardly toward the axis of the mandrel 50 and thereafter axially translated to enter the tenon 76 within its complementary recess 78. The key 86 can thereafter be inserted within the cooperating half keyways 84 for additional security and unitary assembly of segments 62 and 64.

Whether the mandrel 50 is of the independently reciprocal type, in which case it would be supported Within an axial bore in the piston 36 and ram 40, as previously described, or is rigidly attached and permanently extended from the forward face of the ram 46 and axially translatable therewith as a unit, the mandrel 56 in either case must be sufficiently long to extend through substantially the full length of the bore in the billet 7t] and project into the female die 24) at the beginning of an extrusion operation, with the forward assembled segments 62 and 64 of the dummy block 54 in bearing abutment against the rear face of the billet '70 and preferably, but not necessarily, with at least the scavenging flange 66 within the bore in cylinder 24. Advancement of the ram 40 will thereafter first compact or compress the billet 7 6 into circumferential and axial outer surface contact with the inner bore surface of the cylinder 24, as well as into similar contact with the mandrel Ell (FIG. 3). Breakthrough of the billet 70 into the orifice defined between the bearing of the female die 20 and mandrel 50 extending axially into the same, followed by continuing plastic flow of the billet '70 through the aforesaid orifice so formed under the influence of the advancing ram 40, is productive of tubular extruded material, as indicated by reference numeral 92 in FIG. 1.

Penetration of the generally convex profile of the front or working face of the assembled dummy block segments 62 and 64, defined by the aforesaid surfaces 72 and 74 thereof, into the rear face of the charged billet 70, has been discovered to be beneficial in developing a radially inward directed wedging action against radial separation of the segments 62 and 64 during the extrusion operation. In fact the keyway and key construction 8486 securing the dummy block elements 62 and 64 adds little if any restraining force during passage of the segmented dummy block through the bore of cylinder 24.

Completion of the extrusion operation is indicated in phantom broken line construction in FIG. 1, with the tool assembly 18 and extruded product 92 translated into position below the shear 30. It will be observed that the assembled segments 62 and 64 of the composite or segmented dummy block 54 have been axially separated from the one-piece back-up element 56 thereof and have been carried forward with an unextruded normally contaminated heel or butt 94 into position beneath the shear 30, at which location the assembled segments 62 and 64 are recoverable as a unit, subsequently separated by extracting the key 86, and returnable to the breech end of the billet cylinder 24, previously charged with another billet 70, for assembly and installation around the mandrel 50 in position and condition for a subsequent extrusion operation.

It will be manifest to those skilled in extrusion that the segmented dummy block elements 62 and 64 provide a new and novel extrusion method comprising the steps of laterally confining a tubular billet of solid material, such as metals and alloys thereof, as well as many commercial extrudable plastics, with one end face thereof in abutment against the entry face to a die for controlling the exterior configuration of a tubular extruded product to be made from the so confined billet, while providing a mandrel extending axially through said tubular billet into and/or through the exterior contour-controlling die; assembling at least two segments of a dummy block in surrounding relationship on the exposed surface of the mandrel adjacent the exposed end surface of the tubular billet remote to the end face thereof in abutment against the entry face to the die; advancing the assembled dummy block and a generally forwardly extending convex front face thereof into penetrating contact with the rear end face of the otherwise laterally-confined tubular billet to express the same axially through the orifice formed between the die and mandrel extending therethrough to produce a tubular extrusion therefrom; continuing the advancing travel of the dummy block over substantially the entire axial length of the laterally-confined billet, but preferably less than the entire axial billet length to thereby provide a relatively short axial length heel or butt composed of unextruded material of the billet and contaminates thereof, such as oxides accumulated on the exposed surfaces of the initial billet, extrusion lubricant, and the like; interrupting the forward travel of the dummy block on extrusion of the billet to provide a tubular extrusion in integral attachment to the aforesaid heel; removing the tubular extrusion and integral heel axially out of confinement and clear of the mandrel extending axially thereinto; axially separating and recovering the unitarily assembled segmented dummy block elements from front surface embedment within the heel; laterally separating the segments of the recovered dummy block; and thereafter again assembling the segments of the I] dummy block on the exposed surface of the mandrel adjacent the breech end of the charged billet container in position and condition for a subsequent repeat extrusion operation.

It will also be understood by those skilled in extrusion that many metals and alloys, and similar extrudable materials, conventionally responding to extrusion practices, require preheating to aid and improve their plastic deformation. Aluminum and its alloys respond in this respect and extrusion billets thereof are usually preheated to a temperature within the range 700 to 950 F. Under such preheating practices, the dummy block segments are also usually brought up to the preheating temperature of the billet to be extruded, in which case it would be conventional to provide a supply of two or more preheated segmented dummy blocks as spares in the cyclic operation of an extrusion press so equipped.

Manifestly the rear one-piece element 56 of the integrated dummy block 54 may be dispensed with and the segmented elements 62 and 64 employed alone in the practice of the invention. In such latter instances, the eifec tive restraint of the complementary tenon and mortise construction 76-78, against lateral or radial separation of the elements 62 and 64, would be absent and the key and keyway construction 84-86, described above, would be relied upon to obtain unitary assembly of the dummy block elements 62 and 64.

Segmented dummy blocks, constructed in accordance with the hereinabove described invention, have also been successfully employed to scavenge the interior wall of an uncharged billet cylinder to remove the thin surface layer of billet material and/or contaminates thereof adhered thereto and deposited from one or more previous extrusion operations. When so employed, lateral assembly and securement of the segmented elements 62 and 64 of the dummy block, in axial sliding and assembled relationship on the mandrel 50, would follow the practice described above for a working or extrusion stroke of the ram 40.

It will be manifest to those skilled in the extrusion art that the segmented dummy block hereinabove described in terms of its structure and use in extruding practices is equally adaptable to extrusion equipment in which the mandrel, or a forwardly extending contiguous axial portion thereof, is first employed to initially pierce an otherwise solid billet prior to its extrusion in the production of tubular extrusions therefrom.

While specific embodiments of conventional extrusion apparatus have been selected for purposes of illustrating the structure and use in practice of the segmented dummy block of the present invention, it will be understood that other conventional extrusion equipment may be selected with which the new and improved dummy block may be employed, and it is therefore desired and intended that only such limitations be imposed on the appended claims as positively recited therein.

What is claimed is:

1. In an extrusion press for producing tubular extruded products and having a cylinder for laterally confining a tubular billet to be extruded, a female exterior configuration-controlling die in sealing adjacency at one end of the cylinder, a mandrel extending axially from within an aperture in the female die rearwardly beyond the end of the cylinder remote to said female die, and a ram for exerting axial pressure on a tubular billet charged within the cylinder and substantially filling the axial length thereof, the ram having a pressure-exerting end face axially spaced from the end of the tubular billet nearest thereto to expose an axial length of mandrel bridging the distance between the ram end face and cylinder, and a segmented dummy block comprising at least two elements laterally advanceable into surrounding axially translatable abutting assembly on the surface of the exposed axial length of the mandrel, said assembled dummy block elements being selected to provide a frontal area conforming to and substantially filling the transverse area of the cylinder surrounding the mandrel therein.

2. In an extrusion press comprising a laterally-confining billet container, a female exterior contour-controlling die adjacent one end of said container, a mandrel extending axially through said container into said female die, and a ram for exerting pressure on a tubular billet within said container and surrounding said mandrel to extrude the billet through the die orifice formed between the female die and mandrel; the improvement comprising a segmented dummy block installable between the ram and container in surrounding axial sliding relationship on the exposed surface of the mandrel, the individual segments of the dummy block being laterally advanced normal to the axis of the mandrel into contact with the surface thereof, and means for holding the individual segments in surrounding assembled relationship on said mandrel against lateral separation thereof.

3. In an extrusion press comprising a laterally-confining billet container, a female exterior contour-controlling die adjacent one end of said container, a mandrel extending axially through said container into said female die from the remote end of the container, and a mm for exerting pressure on a tubular billet within said container and surrounding said mandrel to extrude the billet through the die orifice formed between the female die and mandrel; the improvement comprising a segmented dummy block installable between the ram and container into surrounding axial sliding relationship on the exposed surface of the mandrel, the individual segments of the dummy block being laterally advanced normal to the axis of and into contact with each other and the surface of the mandrel, means for securing the individual segments in surrounding sliding assembled relationship on said mandrel against lateral separation thereof, and said assembled and installed segmented dummy block having a generally convex frontal surface facing towards the billet container.

4. In an extrusion press comprising a laterally-confining billet container, a female exterior contour-controlling die adjacent one end of said container, a mandrel extending axially through said container into said female die and rearwardly beyond the remote end of the container, and a ram for exerting pressure on a tubular billet within said container and surrounding said mandrel to extrude the billet through the die orifice formed between the female die and mandrel; the improvement comprising a segmented dummy block installable between the ram and container into surrounding axial sliding relationship on the exposed surface of the rearwardly extending mandrel, the individual segments of the dummy block being laterally advanced normal to the axis of and into contact with each other and the surface of the rearwardly extending mandrel, said contacting segments providing a contiguous perimetrical scavenging flange of complementary close sliding tolerance to the interior bore of the billet container, means for securing the individual segments in surrounding sliding assembled relationship on said mandrel, and said installed and assembled segmented dummy block presenting a generally convex frontal surface area facing towards the billet container.

5. In an extrusion press comprising a laterally-confining billet container, a female exterior contour-controlling die adjacent one end of said container, a mandrel extending axially through said container into said female die and rearwardly beyond the remote end of the container, and a ram for exerting pressure on a tubular billet within said container and surrounding said mandrel to extrude the billet through the die orifice formed between the female die and mandrel; the improvement comprising a segmented dummy block installable between the ram and container into axial surrounding sliding relationship on the exposed surface of the mandrel, the individual segments of the dummy block being laterally advanced normal to the axis of and into contact with each other and the surface of the rearwardly extending mandrel to provide a planar front facial area of generally convex form filling the area between the mandrel and bore in the billet container, said contacting segments having a contiguous perimetrical scavenging flange complementary to and of close sliding tolerance within the bore in the billet container, and means for securing the individual segments in surrounding sliding assembled relationship on said mandrel against lateral separation thereof.

6. In an extrusion press comprising a laterally-confining billet container, a female exterior contour-controlling die adjacent one end of said container, a mandrel extending axially through said container into said female die from the remote end of the container, and a ram for exerting pressure on a tubular billet within said container and surrounding said mandrel to extrude the billet through the die orifice formed between the female die and mandrel; the improvement including a three-piece dummy block comprising a one-piece rear element for structural assembly with two segmented forwardly disposed elements, the one-piece element having an axial bore therethrough complementary to the transverse exterior profile of the mandrel and an outer perimetrical configuration appreciably smaller than the bore in the billet container, whereby the one-piece element is axially slidable over the mandrel and non-interferingly translatable through the bore in the billet container, said two segmented elements of the dummy block being configurated on opposing surfaces thereof for laterally advanced surrounding abuting axially slidable assembly on the transverse exterior profile of the mandrel into axial abutting rear facial contact with said one-piece element of the dummy block, said mandrel-surrounding axial abutting assembly of the three-piece dummy block presenting the front facial area of the segmented elements thereof facing towards the breech entrance to the billet container and rear facial area of the one-piece element thereof facing the pressure-exerting end face of the ram, said assembled segmented forward elements of the dummy block having a contiguous perimetrical flange complementary to the bore in the billet container and providing a close tolerance sliding fit therethrough, and a tenon and recess connection between the assembled forward segmented elements and rear one-piece element in axial assembled abutment therebetween.

7. In an extrusion press comprising a laterally-confining bille-t container, a female exterior contour-controlling die adjacent one end of said container, a mandrel extending axially through said container into said female die and rearwardly beyond the remote end of the container, and a ram for exerting pressure on a tubular billet within said container and surrounding said mandrel to extrude the billet through the die orifice formed between the female die and mandrel; the improvement including a three-piece dummy block comprising a one-piece rear element in structural assembly with two segments of a front element thereof, the one-piece element having an axial bore therethrough bushed to slidingly conform to the transverse exterior profile of the mandrel and an outer perimetrical configuration appreciably smaller than the bore in the billet container, whereby the one-piece element is axially slidable over the mandrel and non-interferingly translatable through the bore in the billet container, said two segmented elements of the dummy block being configurated on opposing surfaces thereof for laterally advanced surrounding abutting axially slidable assembly on the trans verse exterior profile of the rearwar-dly extending mandrel into axial abutting rear facial contact with said one-piece element of the dummy block, said mandrel-surrounding axial abutting assembly of the three-piece dummy block presenting the front facial area of the segmented elements thereof facing towards the breech entrance to the billet container and rear facial area of the one-piece element thereof facing the pressure-exerting end face of the ram, said assembled segmented forward elements of the dummy block having a contiguous perimetrical flange complementary to the bore in the billet container and providing a close tolerance sliding fit therethrough, and a tenon and recess axially separable connection between the assembled forward segmented elements and rear one-piece element in axial assembled abutment therebetween.

8. In an extrusion press comprising a laterally-confining billet container, a female exterior contour-controlling die adjacent one end of said container, a mandrel extending axially through said container into said female die from the remote end of the container, and a ram for exerting pressure on a tubular billet within said container and surrounding said mandrel to extrude the billet through the die orifice formed between the female die and mandrel; the improvement including a three-piece dummy block comprising a one-piece rear element in structural abutting as sembly with two segments of a front element thereof, the rear element having an axial bore therethrough bushed to slidingly conform to the transverse exterior profile of the mandrel and an outer perimetrical configuration appreciably smaller than the bore in the billet container, whereby the one-piece element is axially slidable over the mandrel and non-interferingly translatable through the bore in the billet container, said two front elements of the dummy block being configurated on opposing surfaces thereof for lateral advancing and surrounding abutting assembly on the transverse exterior profile of the mandrel in axially slidable relationship thereto into and out of axial abutment with the rear element of the dummy block, said mandrel-surrounding axial abutting assembly of the threepiece dummy block providing a tenon within recess joint between the front segments and rear element thereof and presenting a front facial area of the two forward segmented and assembled elements of convex configuration facing the breech entrance to the billet container, and means in addition to the tenon within recess: joint for unitarily securing the two front segments of the dummy block against lateral separation, said means comprising an oppositely angularly configurated key within a complementary half keyway in each of the two segments.

9. A method of extruding tubular products comprising the steps, laterally confining a tubular billet to be 6X- truded, laterally advancing segments of a dummy block into abutment and surrounding assembly on a mandrel in contiguous extension of a pressure-exerting ram with the mandrel extending axially through the tubular billet into a female die in abutment with an end of the billet remote to the ram, exerting pressure through the ram against the assembled dummy bloc-k and tubular billet to ex-trude the latter through the orifice defined by the female die and mandrel to produce a tubular extrusion in physical embedded end connection with the assembled segments of the dummy block, reciprocating the tubular extrusion and embedded assembled segments of the dummy block unitarily and axially clear of the mandrel, axially separating the assembled segments from embedment with the tubular extrusion, and laterally separating the segments from their abutting assembly in preparation for a subsequent repeat extrusion operation.

10. A method of extruding tubular products comprising the steps, laterally confining a tubular billet to be extruded, laterally advancing segments of a dumy block into abutment and surrounding assembly on a mandrel in conti uous extension of a pressure-exerting ram with the mandrel extending axially through the tubular billet into a female die in abutment with an end of the billet remote to the ram, exerting pressure through the ram against the assembled dummy block and tubular billet to extrude the latter through the orifice defined by the female die and mandrel to produce a tubular extrusion in integral attachment to an unextruded axially short heel of contaminated billet material with the assembled segments of the dummy block pressure-adhered to and slightly embedded within 1 l 1 2 the rear face of the heel, reciprocating the integrated eX- References Cited by the Examiner truded tubular product, heel and pressure-adhered assem- UNITED STATES PATENTS bled segments of the dummy block axially clear of the 1,330,489 2/1920 Neuberth 72 273 mandrel, axially separating the assembled segments of the 5 1,802,785 4/1931 dummy block from pressure-adherence to and embedment With the heel, and thereafter laterally separating the segments from their abutting assembly in preparation for 21 CHARLES LANHAM, Primary Examinersubsequent repeat extrusion operation. H. D. HOINKES, Assistant Examiner.

Singer 72273 2,925,176 2/1960 Wyngaert 72273 

1. IN AN EXTRUSION PRESS FOR PRODUCING TUBULAR EXTRUDED PRODUCTS AND HAVING A CYLINDER FOR LATERALLY CONFINING A TUBULAR BILLET TO BE EXTRUDED, A FEMALE EXTERIOR CONFIRGURATION-CONTROLLING DIE IN SEALING ADJACENCY AT ONE END OF THE CYLINDER, A MANDREL EXTENDING AXIALLY FROM WITHIN AN APERTURE IN THE FEMALE DIE REARWARDLY BEYOND THE END OF THE CYLINDER REMOTE TO SAID FEMALE DIE, AND A RAM FOR EXERTING AXIAL PRESSURE ON A TUBULAR BILLET CHARGED WITHIN THE CYLINDER AND SUBSTANTIALLY FILLING THE AXIAL LENGTH THEREOF, THE RAM HAVING A PRESSURE-EXERTING END FACE AXIALLY SPACED FROM THE END OF THE TUBULAR BILLET NEAREST THERETO TO EXPOSE AN AXIAL LENGTH OF MANDREL BRIDGE ING THE DISTANCE BETWEEN THE RAM END FACE AND CYLINDER, AND A SEGMENTED DUMMY BLOCK COMPRISING AT LEAST TWO ELEMENTS LATERALLY ADVANCEABLE INTO SURROUNDING AXIALLY TRANSLATABLE ABUTTING ASSEMBLY ON THE SURFACE OF THE EXPOSED AXIAL LENGTH OF THE MANDREL, SAID ASSEMBLED DUMMY BLOCK ELEMENTS BEING SELECTED TO PROVIDE A FRONTAL AREA CONFORMING TO AND SUBSTANTIALLY FILLING THE TRANSVERSE AREA OF THE CYLINDER SURROUNDING THE MANDREL THEREIN. 